Phenanthrene Purification: Comparison of Zone Melting and Co‐Crystallization

The purification of phenanthrene is a prerequisite before studying its solid-solid phase transition at the molecular scale. Two purification methods, namely, zone melting and co-crystallization with 3,5-dinitrobenzoic acid, were separately studied and compared, in view of reaching ultrapurity which means a purity of >99.9 mol %. An explanation of the relationship between the efficiency of both techniques by using phase diagrams has been attempted. A novel strategy is proposed to optimize phenanthrene ultrapurification based on a combination of the two methods.